• 关键词：岩溶区  pCO₂  CO₂扩散通量  控制因素  深水水库

• 基金项目：贵州省国内一流学科建设项目"贵州师范大学地理学"（黔教科研发[2017]85号）；国家自然科学基金（No.41263011）；贵州省科学技术基金（黔科合计省合[2012]7005号）

• 曹玉平
• 1. 贵州师范大学地理与环境科学学院, 贵阳 550001;2. 贵州省山地资源与环境遥感应用重点实验室, 贵阳 550001

• 袁热林
• 1. 贵州师范大学地理与环境科学学院, 贵阳 550001;2. 贵州省山地资源与环境遥感应用重点实验室, 贵阳 550001

• 焦树林
• 1. 贵州师范大学地理与环境科学学院, 贵阳 550001;2. 贵州省山地资源与环境遥感应用重点实验室, 贵阳 550001

• 张倩
• 1. 贵州师范大学地理与环境科学学院, 贵阳 550001;2. 贵州省山地资源与环境遥感应用重点实验室, 贵阳 550001

• 邓飞艳
• 1. 贵州师范大学地理与环境科学学院, 贵阳 550001;2. 贵州省山地资源与环境遥感应用重点实验室, 贵阳 550001

• 摘要：以云贵高原岩溶深水水库——万峰湖为例，于2016年9月对该水库水体进行连续走航观测及分层采样，测定水体温度（T）、酸碱度（pH）、电导率（Cond）、总溶解固体物（TDS）、氧化还原电位（ORP）及碱度（ALK），通过水化学平衡原理及亨利定律计算水体二氧化碳分压（pCO₂）.结果表明：干流表层pCO₂为128.84~222.51 Pa，均值为184.03 Pa；支流表层pCO₂为140.32~285.00 Pa，均值为216.78 Pa.剖面上，干流pCO₂为128.84~1076.81 Pa；支流pCO₂为140.32~657.23 Pa，干、支流剖面pCO₂随水深度增加而升高.TDS浓度为203.0~286.7 mg·L^-1，溶解无机碳（DIC）浓度为2.56~3.37 mmol·L^-1.相关分析表明：水体pCO₂与ORP呈显著正相关，分析认为受水生生物作用影响，水生生物消耗表层溶解CO₂使表层水体pCO₂较低.同时，pCO₂与TDS、DIC呈正相关，说明万峰湖流域内溶蚀作用控制的河流碳酸盐体系是影响水体pCO₂的主要原因.干、支流水体pCO₂处于过饱和状态，成为大气CO₂的源.根据Wanninkhof提出的淡水水-气界面交换系数的通量模式，估算干、支流水-气界面CO₂交换速率分别为0.16、0.19 μmol·m^-2·s^-1，其扩散通量干流为9.77~20.84 mmol·m^-2·d^-1，均通量为15.30 mmol·m^-2·d^-1；支流为11.55~27.88 mmol·m^-2·d^-1，均通量为19.72 mmol·m^-2·d^-1.与世界其它河流、水库相比较，水库干、支流二氧化碳扩散通量比热带地区河流Amazon、Curua-Una、Tucurui小；与温带地区黄河相比，扩散通量要大；与亚热带岩溶区水库相比差异不明显.

• Abstract：Water samples were collected by continuous navigation observation and stratified sampling, and their water temperature(T), pH, conductivity(Cond), total dissolved solids(TDS), oxidation-redox potential (ORP), as well as alkalinity(ALK) were determined in situ in Wanfenghu reservoir located in Yunnan-Guizhou Plateau in September 2016. The partial pressure of CO₂ (pCO₂) was calculated using the water-chemical balance and the Henry's law. Results showed:the pCO₂ in surfer water of mainstream and the branch were 128.84~222.51 Pa with mean values of 184.03 Pa and 140.32~285.00 Pa with mean values 216.78 Pa, respectively. In the vertical section, the pCO₂ of the mainstream and the branch were 128.84~1076.81 Pa and 140.32~657.23 Pa, respectively, and they had increasing trend with downwardly. The significant positive correlation between the pCO₂ and ORP suggested that the pCO₂ was controlled by the aquatic photosynthesis which resulted dissolved carbon dioxide consumption and the pCO₂ being lowly in the surfer water. The TDS was 203.0~286.7 mg·L^-1 and DIC was 2.56~3.37 mmol·L^-1. The pCO₂ having a strong positive correlation with TDS and DIC suggested that the main control factor of pCO₂ was the carbonate system because of the strong mechanical erosion and chemical weathering in the Wanfenghu drainage basin. The mainstream and tributary river were the source of atmospheric CO₂ because the pCO₂ of water was supersaturated. According to the flux model of freshwater water-gas exchange coefficient proposed by Wanninkhof, the CO₂ exchange rates were 0.16, 0.19 μmol·m^-2·s^-1 in mainstream and tributary receptivity. The diffusion fluxes of CO₂ were 9.77~20.84 mmol·m^-2·d^-1with mean of 15.30 mmol·m^-2·d^-1, and 11.55~27.88 mmol·m^-2·d^-1 with mean of 19.72 mmol·m^-2·d^-1 in mainstream and tributary respectively. Compared with the other rivers and reservoirs in the world, the carbon dioxide diffusion fluxes in Wanfenghu reservoir and rivers were similar to those of other subtropical karst reservoirs, smaller than those of the tropical rivers of Amazon, Curua-Una and Tucurui, and higher than those of the temperate regions.

• Key words：karst area  partial pressure of CO₂(pCO₂)  CO₂ diffusion flux  control factor  deeply water reservoir

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